Wireless lan communication device and wireless lan communication method

ABSTRACT

[Overview][Problem to be Solved] It is possible to achieve more appropriate retransmission control in wireless LAN systems.[Solution] There is provided a wireless LAN communication device including: a generator that generates a data frame for which a data unit in which an encoding process is performed and a data unit in which a retransmission process is performed are different from each other; and a transmission section that transmits the data frame. The encoding process makes it possible to determine whether or not decoding is successful.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/632,392, filed Jan. 20, 2020, which is based on PCT filingPCT/JP2018/018836, filed May 16, 2018, which claims priority to JP2017-145740, filed Jul. 27, 2017, the entire contents of each areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a wireless LAN communication deviceand a wireless LAN communication method.

BACKGROUND ART

In recent years, various retransmission schemes have been developed ascommunication techniques have been developed. For example, amongwireless communication techniques, a technique related to retransmissioncontrol that is called Hybrid ARQ (Hybrid Automatic repeat-request,referred to below as “HARQ”) has been developed.

For example, PTL 1 below discloses a technique to add HARQ to a wirelessLAN protocol with MAC-based feedback.

CITATION LIST Patent Literature

PTL 1: Japanese Patent No. 5254369

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Here, it is requested to achieve more appropriate retransmission controlin wireless LAN systems. More specifically, data (for example, MPDU (MAClayer Protocol Data Unit)) that is communicated in a wireless LAN systemhas a variable length, and therefore it is necessary to performindividual sequence management when fragment processing is performed forpredetermined access control, making it difficult to perform control. Ithas therefore been difficult to directly apply the above-described HARQto the wireless LAN system.

The present disclosure has been devised in view of the above-describedcircumstances, and provides a novel and improved wireless LANcommunication device and wireless LAN communication method that make itpossible to achieve more appropriate retransmission control in awireless LAN system.

Means for Solving the Problems

According to the present disclosure, there is provided a wireless LANcommunication device including: a generator that generates a data framefor which a data unit in which an encoding process is performed and adata unit in which a retransmission process is performed are differentfrom each other; and a transmission section that transmits the dataframe. The encoding process makes it possible to determine whether ornot decoding is successful.

In addition, according to the present disclosure, there is provided awireless LAN communication method that is executed by a computer. Thewireless LAN communication method includes: generating a data frame forwhich a data unit in which an encoding process is performed and a dataunit in which a retransmission process is performed are different fromeach other; and transmitting the data frame. The encoding process makingit possible to determine whether or not decoding is successful.

In addition, according to the present disclosure, there is provided awireless LAN communication device including: a reception section thatreceives a data frame for which a data unit in which an encoding processis performed and a data unit in which a retransmission process isperformed are different from each other; and a reception process sectionthat performs a reception process including decoding the data frame. Theencoding process makes it possible to determine whether or not decodingis successful.

In addition, according to the present disclosure, there is provided awireless LAN communication method that is executed by a computer. Thewireless LAN communication method includes: receiving a data frame forwhich a data unit in which an encoding process is performed and a dataunit in which a retransmission process is performed are different fromeach other; and performing a reception process including decoding thedata frame. The encoding process makes it possible to determine whetheror not decoding is successful. Effects of the Invention

As described above, according to the present disclosure, it is possibleto achieve more appropriate retransmission control in a wireless LANsystem.

It should be noted that the above-described effects are not necessarilylimitative. Any of the effects indicated in this description or othereffects that may be understood from this description may be exerted inaddition to the above-described effects or in place of theabove-described effects.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a diagram illustrating an example of a configuration of awireless LAN system according to the present embodiment.

FIG. 2 is a diagram illustrating an example of a configuration of aphysical layer header and a physical layer trailer.

FIG. 3 is a diagram illustrating an example of the configuration of thephysical layer header and the physical layer trailer.

FIG. 4 is a diagram illustrating an example of a configuration of MPDU.

FIG. 5 is a diagram describing an overview of an encoding process.

FIG. 6 is a diagram describing an overview of a decoding process.

FIG. 7 is a diagram describing an example of a combining process usingretransmitted MPDU.

FIG. 8 is a diagram describing an example of the combining process usingthe retransmitted MPDU.

FIG. 9 is a diagram describing an example of the combining process usingthe retransmitted MPDU.

FIG. 10 is a diagram describing an example of a combining process usingrepeatedly retransmitted MPDU.

FIG. 11 is a diagram describing an example of the combining processusing the repeatedly retransmitted MPDU.

FIG. 12 is a block diagram illustrating an example of a functionalcomponent of AP and STA.

FIG. 13A is a flowchart illustrating an example of a transmissionoperation.

FIG. 13B is a flowchart illustrating an example of the transmissionoperation.

FIG. 14A is a flowchart illustrating an example of a receptionoperation.

FIG. 14B is a flowchart illustrating an example of the receptionoperation.

FIG. 15 is a diagram describing an overview of an encoding process in acase where a block length is greater than that of MPDU.

FIG. 16 is a diagram describing an overview of a decoding process in acase where a block length is greater than that of MPDU.

FIG. 17 is a diagram illustrating an example of a configuration of aphysical layer header and a physical layer trailer in a case where thepresent disclosure is applied to A-MSDU.

FIG. 18 is a diagram describing an overview of an encoding process inthe case where the present disclosure is applied to the A-MSDU.

FIG. 19 is a diagram describing an overview of a decoding process in thecase where the present disclosure is applied to the A-MSDU.

FIG. 20 is a diagram describing a case where one MPDU includes aplurality of aggregated MSDUs.

FIG. 21 is a diagram describing a case where MPDUs including a pluralityof aggregated MSDUs are further aggregated.

FIG. 22 is a diagram describing a variation of a storage position of thephysical layer header.

FIG. 23 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 24 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 25 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 26 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 27 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 28 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 29 is a diagram describing a variation of the storage position ofthe physical layer header.

FIG. 30 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 31 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus.

FIG. 32 is a block diagram illustrating an example of a schematicconfiguration of a wireless access point.

MODES FOR CARRYING OU THE INVENTION

The following describes a preferred embodiment of the present disclosurein detail with reference to the accompanying drawings. It should benoted that, in this description and the accompanying drawings,components that have substantially the same functional configuration areindicated by the same reference signs, and thus redundant descriptionthereof is omitted.

It should be noted that the description is given in the following order.

-   1. Background-   2. Wireless LAN System according to Embodiment of Present Disclosure-   3. Modification Examples-   4. Application Examples-   5. Conclusion

1. BACKGROUND

First, the background of the present disclosure is described.

As described above, in recent years, various retransmission schemes havebeen developed as communication techniques have been developed. Forexample, among wireless communication techniques, a technique related toretransmission control that is called HARQ has been developed. Forexample, in a public wireless communication system, an appropriate blocklength is defined depending on the number of subcarriers in a physicallayer, and retransmission control is performed with this block lengthused as a unit. The block length used as a unit for retransmissioncontrol is then a fixed length, and the retransmission control orsequence management is thus easy.

Here, it is requested to achieve more appropriate retransmission controlin wireless LAN systems. More specifically, data (for example, MPDU)that is communicated in a wireless LAN system has a variable length, andtherefore fragment processing is difficult for predetermined accesscontrol, making it difficult to directly apply the above-described HARQto the wireless LAN system. For example, in a case where HARQ is appliedto a wireless LAN system, block partition positions in variable-lengthdata that is communicated in the wireless LAN system are different fromthose of HARQ.

Furthermore, the retransmission control is performed in the wireless LANsystem with MPDU used as a unit. Accordingly, even if HARQ is used forprocessing in a lower layer than the MAC layer, the retransmissioncontrol is not performed in a unit corresponding to HARQ. For example,if there is an error in one HARQ block, whole MPDU that is larger thanthe HARQ block is retransmitted, preventing improvement in efficiency oftransmission path usage.

Furthermore, a frame aggregation technique is applied to the wirelessLAN system to enable aggregation of a plurality of data units, and thusit is possible to reduce frame transmission overhead and improvetransmission efficiency. Among frame aggregation techniques, a techniquecalled A-MPDU (aggregated MPDU) aggregation has been consideredparticularly effective and generally and widely used. This techniqueaggregates a plurality of MPDUs as one physical layer frame.

In a case where HARQ is applied to an A-MPDU frame, block partitionpositions in each MPDU are different from those of HARQ, because thelength of the MPDU is variable as described above. A receiver istherefore unable to perform a simple combining process of retransmittedMPDU and MPDU received in the past.

Furthermore, delimiter information including data length information ofthe MPDU in an A-MPDU configuration is appended at the beginning the ofMPDU. The receiver that receives the A-MPDU recognizes boundaries of therespective MPDUs on the basis of the data length information. If thedata length information included in the delimiter information isincorrect, the receiver is thus unable to correctly recognize boundariesof the respective MPDUs. Consequently, the receiver fails in a receptionprocess of MPDU located at or after the boundary that has not beencorrectly recognized, and discards such MPDU.

The discloser of the present application has devised the presentapplication in view of the circumstances described above. The presentdisclosure makes it possible to achieve more appropriate retransmissioncontrol in wireless LAN systems. The present disclosure also enables areception process of MPDU to be successful even in a case where datalength information of MPDU included in delimiter information in anA-MPDU configuration is incorrect. The following describes a wirelessLAN system according to an embodiment of the present disclosure.

2. WIRELESS LAN SYSTEM ACCORDING TO EMBODIMENT OF PRESENT DISCLOSURE

The background of the present disclosure has been described above. Next,a wireless LAN system according to an embodiment of the presentdisclosure is described.

2-1. Configuration

First, the configuration of the wireless LAN system according to thepresent embodiment is described with reference to FIG. 1.

As illustrated in FIG. 1, the wireless LAN system according to thepresent embodiment includes access point devices (each referred to belowas “AP (Access Point)”) 200 and station devices (each referred to belowas “STA (Station)”) 100. One AP 200 and one or more STAs 100 then form abasic service set (referred to below as “BSS (Basic Service Set)”) 10.

The wireless LAN system according to the present embodiment may beinstalled in any places. For example, the wireless LAN system accordingto the present embodiment may be installed in office buildings,residential houses, business or public establishments, and the like.

In addition, an area of the BSS 10 according to the present embodimentmay overlap with an area of another BSS 10 (referred to below as “OBSS(Overlap Basic Service Set)”) whose frequency channel overlaps with thefrequency channel used by the BSS 10. In that case, a signal transmittedfrom the STA 100 located in the overlapping area may interfere with asignal transmitted from the OBSS. Referring to an example illustrated inFIG. 1, an area of BSS 10 a overlaps with a portion of an area of BSS 10b that is OBSS, and STA 100 b is located in the overlapping area. Inthis case, a signal transmitted from the STA 100 b belonging to the BSS10 a may interfere with a signal transmitted from AP 200 b or STA 100 cbelonging to the BSS 10 b. It should be noted that FIG. 1 illustrates,as an example, a case where other wireless LAN systems causeinterference therebetween, but this is not limitative. For example, acommunication base station and a communication terminal in anothercommunication system other than wireless LAN may overlap with the BSS 10a to cause interference.

Each of the APs 200 is a wireless LAN communication device that iscoupled to an external network and provides the STA 100 withcommunication with the external network. For example, the AP 200 iscoupled to the Internet and provides communication between the STA 100and a device on the Internet or a device to be coupled via the Internet.

The STA 100 is a wireless LAN communication device that communicateswith the AP 200. The STA 100 may be any communication device. Forexample, the STA 100 may be a display having a display function, amemory having a storage function, a keyboard and a mouse each having aninput function, a speaker having a sound output function, or asmartphone having an advanced calculation processing execution function.

It should be noted that the functionality of the present disclosure maybe achieved by either the AP 200 or the STA 100. That is, the AP 200 andthe STA 100 may have the same functional components. Either or both ofthe AP 200 and the STA 100 may therefore be referred to below as“transmitter” or “receiver”.

2-2. Overview of Functionality

The configuration of the wireless LAN system according to the presentembodiment has been described above. Next, the overview of thefunctionality of the wireless LAN system according to the presentembodiment is described.

In the wireless LAN system according to the present embodiment, a dataframe is communicated in which a data unit in which an encoding processis performed and a data unit in which a retransmission process isperformed are different from each other. The encoding process makes itpossible to determine whether or not decoding is successful.

More specifically, the transmitter generates A-MPDU in which a pluralityof MPDUs is aggregated, and appends an error correcting code to theA-MPDU in units of predetermined blocks. The receiver performs areception process (including a decoding process) of the A-MPDU andspecifies a block for which the reception process has been unsuccessful.Thereafter, the receiver performs a combining process of respectiveerror-free blocks from MPDU for which the reception process has beenunsuccessful and retransmitted MPDU to restore the MPDU, therebysucceeding in the reception process.

Furthermore, the transmitter may include, in a physical layer header(such as a PLCP header), information for use in identification of theaggregated MPDU in the A-MPDU or append a physical layer trailer (suchas a PLCP trailer) including the same information to the end of a dataframe. Here, the information for use in identification of MPDU, forexample, means the data length, the sequence number, and the like of theMPDU. This enables the wireless LAN system to identify each MPDU even ifthe data length information included in the delimiter information isincorrect. Furthermore, including the information not only in thephysical layer header, but also in the physical layer trailer enablesthe wireless LAN system to identify each MPDU included in the A-MPDU aslong as the physical layer trailer is successfully received even if thephysical layer header is unsuccessfully received.

Furthermore, the wireless LAN system is able to store a plurality ofidentical retransmission MPDUs in A-MPDU as long as a frameconfiguration of the A-MPDU has the capacity. This enables the wirelessLAN system to increase the possibility of succeeding in the combiningprocess.

It should be noted that it is merely an example that the data frame tobe communicated is A-MPDU, but this is not limitative. For example, thedata frame to be communicated may be A-MSDU, non-aggregated MPDU, ornon-aggregated MSDU.

2-3. Details of Functionality

The overview of the functionality of the wireless LAN system accordingto the present embodiment has been described above. Next, the details(including a frame configuration and the like) of the functionality ofthe wireless LAN system according to the present embodiment aredescribed. First, a physical layer header and a physical layer trailerof A-MPDU are described with reference to FIG. 2.

As illustrated in FIG. 2, the transmitter generates a data frame inwhich the physical layer header is appended after a predeterminedpreamble (Preamble) or the physical layer trailer is appended after aplurality of aggregated MPDUs (eight MPDUs (1st MPDU to 8th MPDU) areaggregated in the diagram).

The physical layer header and the physical layer trailer includeinformation such as recipient address identification information(RXAID), transmitter address identification information (TXAID),encoding format information (Type), encoding process block lengthinformation (Block Size), data length information (Total Length) of theentire A-MPDU, information (MPDU Count) of the number of MPDUs to beaggregated, sequence number information (Seq. No.) of the MPDUs and datalength information (Length) of the MPDU as the information for use inidentification of each MPDU, and an error detection code (CRC). Itshould be noted that FIG. 2 is merely an example, but the configurationof the physical layer header and the physical layer trailer of theA-MPDU is not limited thereto.

Next, variations of a physical layer header and a physical layer trailerof A-MPDU are described with reference to FIG. 3. As illustrated in FIG.3, the sequence number information (Seq. No.) of the MPDUs in FIG. 2 maybe replaced with a starting sequence number (Start Sequence) andinformation (Sequence Bitmap) indicating the sequence number of thesubsequent MPDU in a bitmap format. This eliminates the need to appendthe sequence number information (Seq. No.) of MPDU to each MPDU, andthus enables the transmitter to reduce the volume of A-MPDU information.

Next, the configuration of MPDU is described with reference to FIG. 4.As illustrated in FIG. 4, the MPDU includes delimiter information(Delimiter), protocol data unit (MAC Layer Protocol Data Unit) of apredetermined MAC layer, and an error detection code (CRC). Thedelimiter information then includes data length information (MPDULength) of MPDU, an error detection code (CRC), delimiter identificationinformation (Delimiter Signature) for use in identification of thedelimiter information, and a reserved field (Reserved). It should benoted that FIG. 4 is merely an example, but the configuration of MPDU isnot limited thereto.

Next, an overview of an encoding process is described with reference toFIG. 5.

In an example illustrated in FIG. 5, the transmitter targets, for theencoding process, data obtained by aggregating first MPDU (1st MPDU) tofourth MPDU (4th MPDU) and appending Padding (Pad) thereto asappropriate.

The transmitter then performs the encoding process using, for example,an RS (255, 239) code (code length: 255 symbols, data length: 239symbols, parity length: 16 symbols), which is a kind of Reed-Solomoncodes, as a process of a predetermined encoding unit. In this case, thetransmitter partitions a data string configured as the A-MPDU on a239-byte boundary, generates 16-byte redundancy codes (FEC 1 to FEC 12),and combines them to generate data having 255-byte blocks. Thus,2880-byte data (0 to 287) is changed to 3072-byte data (0 to 3071) asillustrated in FIG. 5.

The transmitter then generates a data frame obtained by appending thepredetermined preamble (Preamble), the physical layer header (Header),and the physical layer trailer (Trailer) to the data generated asdescribed above.

It should be noted that FIG. 5 is merely an example, but any encodingprocess may be employed as long as the encoding process makes itpossible to determine whether or not decoding is successful.

Next, an overview of a decoding process is described with reference toFIG. 6.

The receiver detects the predetermined preamble (Preamble), recognizesthat the received data frame is the data frame according to the presentdisclosure on the basis of the information included in the subsequentphysical layer header (Header) or physical layer trailer (Trailer), andperforms the decoding process according to the present disclosure.

First, the receiver acquires various parameters included in the physicallayer header (Header) or the physical layer trailer (Trailer), andgrasps the block length of the encoding process on the basis of theencoding format information (Type) or the like of the parameters. Thereceiver then performs error detection and error correction as a processof a predetermined encoding unit by extracting redundancy informationfrom the encoded information. That is, the receiver performs the errordetection and the error correction by extracting 0 to 239-byteinformation from 0 to 255-byte information. Thus, the receiver extractsthe 2880-byte data (0 to 2879) from the 3072-byte data (0 to 3071) asillustrated in FIG. 6.

The receiver then stores a block for which an error has been detectedand the error correction has been unsuccessful. More specifically, thereceiver specifies MPDU for which the error correction has beenunsuccessful and a range in the MPDU for which the error correction hasbeen unsuccessful on the basis of the data length information (Length)of each MPDU and the sequence number information (Seq. No.) of each MPDUincluded in the physical layer header (Header) or the physical layertrailer (Trailer), and stores the information.

The receiver then requests the transmitter to retransmit the MPDU forwhich the error correction has been unsuccessful, and restoreserror-free MPDU by combining respective error-free blocks from theretransmitted MPDU and the MPDU transmitted in the past, therebysucceeding in the reception process.

Next, an example of the combining process of MPDUs is described withreference to FIGS. 7 to 11.

First, the receiver receives A-MPDU obtained by aggregating four MPDUs(1st MPDU to 4th MPDU) illustrated in FIG. 7 and performs the receptionprocess including the decoding process on the A-MPDU.

It is then assumed that the receiver detects an error in a block in thethird MPDU (3rd MPDU) and fails in the error correction. Morespecifically, it is assumed that the receiver fails in the errorcorrection of a block ranging from the 1440th byte to the 1679th bytebefore the encoding process is performed on the A-MPDU (a blockcorresponding to a range from the 96th byte to the 335th byte in thethird MPDU). It should be noted that the reception process for the MPDUsother than the third MPDU is successful.

The receiver notifies the transmitter of the successful receptionprocess for the MPDUs other than the third MPDU by transmitting apredetermined response signal. It should be noted that the predeterminedresponse signal may be, for example, block ACK (ACKnowledgement), but isnot limited thereto.

The transmitter that receives the response signal grasps that thereception process of the MPDUs other than the third MPDU has beensuccessful (in other words, the reception process for the third MPDU mayhave been unsuccessful) and retransmits the third MPDU.

For example, as illustrated in FIG. 8, the transmitter transmits, to thereceiver, A-MPDU obtained by aggregating third MPDU (Resend 3rd MPDU)for retransmission, and the fifth MPDU (5th MPDU) and the sixth MPDU(6th MPDU) to be newly transmitted.

It is assumed that the receiver detects errors in a block including theend of the retransmitted third MPDU (Resend 3rd MPDU) and the beginningportion of the fifth MPDU (5th MPDU) and in a block included near theend of the fifth MPDU (5th MPDU), and fails in the error correction asillustrated in FIG. 8.

More specifically, it is assumed that the receiver fails in the errorcorrection for a block ranging from the 720th byte to the 959th bytebefore the encoding process is performed on the A-MPDU (a blockcorresponding to a range from the 720th byte to the 863rd byte in thethird MPDU and a block corresponding to a range from the 0th byte to the95th byte of the fifth MPDU) and a block ranging from the 1680th byte tothe 1919th byte (a block corresponding to a range from the 816th byte tothe 1055th byte of the fifth MPDU).

The receiver then performs the combining process using the third MPDUtransmitted in the past and the retransmitted third MPDU. Morespecifically, the receiver combines respective error-free portions ofthe third MPDU (3rd MPDU) transmitted in the past and the retransmittedthird MPDU (Resend 3rd MPDU). For example, as illustrated in FIG. 9, thereceiver combines the 0th byte to the 479th byte of the retransmittedthird MPDU (Resend 3rd MPDU) and the 480th byte to the 863rd byte of thethird MPDU (3rd MPDU) transmitted in the past to restore error-freeMPDU. It should be noted that any portions may be used for the combiningprocess as long as the portions are error-free. For example, the 0thbyte to the 719th byte of the retransmitted third MPDU (Resend 3rd MPDU)and the 720th byte to the 863rd byte of the third MPDU (Resend 3rd MPDU)transmitted in the past may be used for the combining process.

The receiver restores the third MPDU through the combining process andsucceeds in the reception process. Accordingly, the receiver notifiesthe transmitter of that by transmitting a predetermined response signal.

The above-described combining process enables the wireless LAN system toachieve more appropriate retransmission control. More specifically, evenif a block in MPDU includes an error, the receiver is able to useerror-free portions of the MPDU for the combining process instead ofdiscarding the whole MPDU. It is therefore possible to restoreerror-free MPDU with a higher probability. Furthermore, the receiver isable to perform the combining process without depending on the blocklength of the encoding process by managing an error-containing portionof the MPDU in units of bytes.

Although an example of the case where A-MPDU includes one MPDU forretransmission has been described above, A-MPDU may include a pluralityof identical MPDUs for retransmission. For example, the transmitter maystore a plurality of identical MPDUs for retransmission in A-MPDU aslong as the frame configuration of the A-MPDU has the capacity.

Now, a case where A-MPDU includes a plurality of identical MPDUs forretransmission is described with reference to FIG. 10. FIG. 10illustrates another A-MPDU to be transmitted after the A-MPDUillustrated in FIG. 8.

The transmitter that receives a predetermined response signal from thereceiver grasps that the reception process of the fifth MPDU may havebeen unsuccessful, and retransmits the fifth MPDU. The transmitter thenstores a fifth MPDU (Resend 5th MPDU) for retransmission and the seventhMPDU (7th MPDU) to be newly transmitted as illustrated in FIG. 10. Thetransmitter then repeatedly stores the fifth MPDU (Repeat 5th MPDU) forretransmission in the A-MPDU if the A-MPDU has the capacity to have thefifth MPDU (Resend 5th MPDU) for retransmission repeatedly storedtherein. It should be noted that FIG. 10 illustrates a case where twoidentical MPDUs for retransmission are stored, but any number ofidentical MPDUs for retransmission may be stored. The transmittertransmits the A-MPDU obtained by aggregating these MPDUs to thereceiver.

It is assumed that the receiver detects errors in blocks included in thefifth MPDU (Resend 5th MPDU) for retransmission and the repeatedlyretransmitted fifth MPDU (Repeat 5th MPDU), and fails in the errorcorrection. More specifically, it is assumed the receiver fails in theerror correction in a block ranging from the 480th byte to the 959thbyte before the encoding process is performed on the A-MPDU, a blockranging from the 1920th byte to the 2159th byte before the encodingprocess is performed on the A-MPDU (a block corresponding to a rangefrom the 384th byte to the 623rd byte in the repeatedly retransmittedfifth MPDU (Repeat 5th MPDU)), and a block ranging from the 2640th byteto the 2879th byte before the encoding process is performed on theA-MPDU (a block corresponding to a range from the 1104th byte to the1152nd byte in the repeatedly retransmitted fifth MPDU (Repeat 5thMPDU)).

The receiver then combines respective error-free portions of the fifthMPDU (5th MPDU) transmitted in the past, the fifth MPDU (Resend 5thMPDU) for retransmission, and the repeatedly retransmitted fifth MPDU(Repeat 5th MPDU). For example, as illustrated in FIG. 11, the receivercombines the 0th byte to the 479th byte of the fifth MPDU (Resend 5thMPDU) for retransmission, the 480th byte to the 815th byte and the1056th byte to the 1151st byte of the fifth MPDU (5th MPDU) transmittedin the past, and the 816th byte to the 1055th byte of the repeatedlyretransmitted fifth MPDU (Repeat 5th MPDU) to restore error-free MPDU.It should be noted that any portions may also be used for the combiningprocess in this example as long as the portions are error-free.

The receiver restores the fifth MPDU through the combining process andsucceeds in the reception process. Accordingly, the receiver notifiesthe transmitter of that by transmitting a predetermined response signal.

Repeatedly storing the MPDU for retransmission enables the wireless LANsystem to increase the possibility of succeeding in the combiningprocess and more effectively use the transmission path.

2-4. Functional Component

The details of the functionality of the wireless LAN system according tothe present embodiment have been described above. Next, functionalcomponents of the AP 200 and the STA 100 are described with reference toFIG. 12.

It should be noted that the STA 100 and the AP 200 may include the samefunctional components as described above. The following therefore mainlydescribes functional components of the STA 100 and additionallydescribes functional components specific to the AP 200. Furthermore, thefunctional components described below are merely an example, but thefunctional components of the STA 100 and the AP 200 are not particularlylimited. For example, functional components described below may beomitted as appropriate, or other functional components may be added.

As illustrated in FIG. 12, the STA 100 includes a wireless communicationunit 110, a wireless interface 120, a controller 130, a wired interface140, an input unit 150, and an output unit 160.

(Wireless Communication Unit 110)

The wireless communication unit 110 has a functional component thatperforms all processes related to wireless communication. As illustratedin FIG. 12, the wireless communication unit 110 includes an antennacontroller 111, a reception process section 112, an MPDU processor 113,a reception buffer 114, a transmission process section 115, an MPDUprocessor 116, and a transmission buffer 117.

(Antenna Controller 111)

The antenna controller 111 has a functional component that controls atleast one antenna to transmit and receive wireless signals. For example,the antenna controller 111 functions as a reception section thatreceives a wireless signal transmitted from another communication deviceby controlling the antenna and provides the reception process section112 with a signal obtained by performing a conversion process on thewireless signal to a reception level that allows extraction of abaseband signal in a subsequent process. Furthermore, the antennacontroller 111 functions as a transmission section that transmits atransmission signal generated by the transmission process section 115 bycontrolling transmission power as necessary to more reliably cause thetransmission signal to reach a destination device.

(Reception Process Section 112)

The reception process section 112 performs the reception process on areception signal provided from the antenna controller 111. For example,the reception process section 112 outputs a baseband signal byperforming analog processing and down-conversion on the reception signalobtained from the antenna. The reception process section 112 thenextracts A-MPDU included in the baseband signal. The reception processsection 112 then performs the decoding process in a block unit of theencoding process to perform the error detection and error correctionprocess. The reception process section 112 provides the extracted A-MPDUor the like to the MPDU processor 113.

(MPDU Processor 113)

The MPDU processor 113 performs an MPDU-related process in the receptionprocess. For example, the MPDU processor 113 separates each MPDU fromthe A-MPDU by using the sequence number information (Seq. No.) of theMPDUs and the data length information (Length) of the MPDUs acquiredfrom the physical layer header or the physical layer trailer. It shouldbe noted that the MPDU processor 113 may separate each MPDU from theA-MPDU by using the data length information (MPDU Length) of the MPDUsacquired from the delimiter information (Delimiter) of each MPDU.

Furthermore, the MPDU processor 113 performs a process on MPDU for whichthe error correction has been unsuccessful. More specifically, as thedecoding process of a predetermined encoding unit, the MPDU processor113 specifies MPDU for which the error correction has been unsuccessfuland a range in the MPDU for which the error correction has beenunsuccessful, and stores the information. The MPDU processor 113 thenrestores error-free MPDU by combining respective error-free portions ofthe MPDU and retransmitted MPDU (and repeatedly retransmitted MPDU) asthe combining process. In a case where successfully restoring theerror-free MPDU, the MPDU processor 113 then temporarily stores the MPDUin the reception buffer 114.

Furthermore, the MPDU processor 113 provides any application with theMPDU (or data included in the MPDU) for which the reception processincluding the decoding process and the combining process have beensuccessful through the wireless interface 120 or the like.

(Reception Buffer 114)

The reception buffer 114 has a functional component that temporalitystores the restored MPDU. Furthermore, the reception buffer 114 maytemporality store a portion, which is free from an error in the decodingprocess of a predetermined encoding unit, of the MPDU for which theerror correction has been unsuccessful. The reception buffer 114includes a memory that stores the information.

(Transmission Process Section 115)

The transmission process section 115 performs the transmission processof A-MPDU generated by the MPDU processor 116. More specifically, thetransmission process section 115 performs the encoding process on theA-MPDU generated by the MPDU processor 116. The encoding process uses anRS (255, 239) code or the like. That is, as a process of a predeterminedencoding unit, the transmission process section 115 partitions dataconfigured as the A-MPDU on the basis of a block length and appendsredundancy codes (such as FECs) thereto. Furthermore, the transmissionprocess section 115 appends the physical layer header, the physicallayer trailer, or the like to the data with the redundancy codesappended thereto, thereby generating transmission data.

The transmission process section 115 then generates a baseband signal byperforming a modulation process on the transmission data and generates atransmission signal by performing up-conversion on the baseband signal.The transmission process section 115 provides the transmission signal tothe antenna controller 111.

(MPDU Processor 116)

The MPDU processor 116 performs an MPDU-related process in thetransmission process. For example, the MPDU processor 116 usesinformation stored in the transmission buffer 117 to construct MPDUhaving a MAC header appended thereto. The MAC header includesdestination information or the like. The MPDU processor 116 then setsthe sequence number information (Seq. No.) for each constructed MPDU tomanage the data length information (Length) of the MPDU.

Further, the MPDU processor 116 also functions as a generator thatgenerates A-MPDU by aggregating MPDUs until a predetermined data lengthis reached or a predetermined number of blocks is reached. In addition,as described above, the MPDU processor 116 may store a plurality ofidentical MPDUs for retransmission in A-MPDU as long as the frameconfiguration of the A-MPDU has the capacity.

(Transmission Buffer 117)

The transmission buffer 117 has a functional component that temporarilystores information that is wirelessly transmitted and provided from anyapplication through the wireless interface 120. The transmission buffer117 includes a memory that stores the information.

(Wireless Interface 120)

The wireless interface 120 is an interface for the wirelesscommunication unit 110 and is a functional component that allowsinformation to be exchanged between the wireless communication unit 110and any application.

(Controller 130)

The controller 130 is a functional component that centrally manages allprocesses by the STA 100. The control unit 130 is achieved by various ICchips and the like each including CPU (Central Processing Unit), ROM(Read Only Memory), RAM (Random Access Memory), and the like forexample.

(Wired Interface 140)

The wired interface 140 is, for example, an interface for any externaldevice, and is a functional component that allows information to beexchanged between the STA 100 and the external device. It should benoted that the wired interface 240 is indispensable for the AP 200because the wired interface 240 functions as an adapter for coupling tothe Internet.

(Input Unit 150)

The input unit 150 is a functional component that receives input ofvarious kinds of information. For example, the input unit 150 includesan input means such as a touch panel, a button, a keyboard, or amicrophone, and allows a user to input various kinds of information byusing these input means. It should be noted that the AP 200 may omit theinput unit 150 or the input unit 150 may have a simpler configuration.

(Output Unit 160)

The output unit 160 is a functional component that outputs various kindsof information. For example, the output unit 160 includes a displaymeans such as a display or a sound output means such as a speaker, andcauses the display or the like to display desired information or causesthe speaker or the like to generate desired sound information on thebasis of a control signal from the controller 130. It should be notedthat the AP 200 may omit the output unit 160 or the output unit 160 mayhave a simpler configuration.

2-5. Operation

The functional components of the AP 200 and the STA 100 have beendescribed above. Next, operations of the AP 200 and the STA 100 aredescribed. It should be noted that the functionality of the presentdisclosure may be achieved by either the STA 100 or the AP 200 asdescribed above. The following therefore describes, as an example, theoperation of the STA 100 functioning as a transmitter and a receiver.

First, the operation of the STA 100 functioning as the transmitter isdescribed with reference to FIGS. 13A and 13B.

At step S1000, the transmission buffer 117 stores information that iswirelessly transmitted and provided from any application through thewireless interface 120. At step S1004, the MPDU processor 116 acquiresdestination information of a transmission signal. In a case where adestination receiver is compatible with the technology of the presentdisclosure (step S1008/Yes), the MPDU processor 116 sets the data lengthinformation (Total Length) of the entire A-MPDU at step S1012.

The MPDU processor 116 then determines whether or not a total value ofthe data lengths of MPDUs to be stored reaches the data length of theentire A-MPDU set in the preceding step. In a case where the total valueof the data lengths of the MPDUs to be stored does not reach the datalength of the entire A-MPDU, but it is possible to add MPDU (stepS1016/Yes), and in a case where there is MPDU for retransmission (stepS1020/Yes), the MPDU processor 116 stores the MPDU for retransmission inthe A-MPDU at step S1040. The process then returns to step S1016.

In a case where the total value of the data lengths of the MPDUs to bestored does not reach the data length of the entire A-MPDU set in thepreceding step, but it is possible to add MPDU (step S1016/Yes), and ina case where there is no MPDU for retransmission (step S1020/No), theMPDU processor 116 stores the MPDU that have not yet been transmitted inthe A-MPDU in order of sequence numbers at step S1024.

In a case where the total value of the data lengths of the MPDUs to bestored does not reach the data length of the entire A-MPDU set in thepreceding step, but it is possible to add MPDU even after the MPDU thathave not yet been transmitted are stored in the A-MPDU (step S1028/Yes),the MPDU processor 116 acquires MPDU stored at the beginning of theA-MPDU again from the transmission buffer 117 at step S1032, andrepeatedly stores the MPDU in the A-MPDU at step S1036. The process thenreturns to step S1016. That is, the MPDU processor 116 repeatedly storesa MPDU for retransmission and MPDU that has not yet been transmitted inthe A-MPDU in this order of priority as long as the frame configurationof the A-MPDU has the capacity.

In a case where the frame configuration runs out of the capacity becausethe total value of the data lengths of the MPDUs to be stored comesclose to the data length of the entire A-MPDU set in the preceding step,and it is no longer possible to add MPDU at step S1016 and step S1028(step S1016/No and step S1028/No), the MPDU processor 116 determines thenecessity of Padding at step S1044. In a case where the MPDU processor116 determines that Padding is necessary (step S1044/Yes), the MPDUprocessor 116 appends Padding to the end of the A-MPDU at step S1048.

Thereafter, the transmission process section 115 sets a block length forthe encoding process using an RS(255,239) code or the like at stepS1052, and partitions the data configured as the A-MPDU on the basis ofthe block length and appends redundancy codes (such as FECs) at stepS1056.

Thereafter, the transmission process section 115 acquires the datalength information (Length) of each MPDU at step S1060, constructs aphysical layer header and a physical layer trailer including encodingprocess parameters and the like, and appends the physical layer headerand the physical layer trailer to the A-MPDU at step S1064. At stepS1068, the antenna controller 111 transmits, as a physical layer frame,a signal having the physical layer header and the physical layer trailerappended thereto. The process then ends.

It should be noted that, in a case where the destination receiver is notcompatible with the technology of the present disclosure at step S1008(step S1008/No), the MPDU processor 116 determines whether or not it ispossible to configure existing A-MPDU at step S1072. In a case where theMPDU processor 116 determines that it is possible to configure existingA-MPDU (step S1072/Yes), the MPDU processor 116 stores MPDU in theA-MPDU at step S1076.

At step S1080, the MPDU processor 116 determines the necessity ofPadding. In a case where the MPDU processor 116 determines that Paddingis necessary (step S1080/Yes), the MPDU processor 116 appends Padding tothe end of the A-MPDU at step S1048, and the process moves to stepS1068. That is, the antenna controller 111 transmits the generatedsignal as a physical layer frame, and the process ends. It should benoted that the above-described flowchart is merely an example, and ismodifiable as appropriate.

Next, the operation of the STA 100 functioning as the receiver isdescribed with reference to FIGS. 14A and 14B.

At step S1100, the reception process section 112 detects a predeterminedpreamble (Preamble), thereby detecting a wireless signal. At step S1104,the reception process section 112 determines whether or not the detectedwireless signal is compatible with the present disclosure on the basisof all or a portion of the information included in the physical layerheader or the arrangement of the physical header. In a case where thedetected wireless signal is compatible with the present disclosure (stepS1104/Yes), the reception process section 112 acquires parametersincluded in the physical layer header at step S1108. In a case where thereception process section 112 fails to decode the physical layer headercorrectly, the reception process section 112 alternatively acquiresparameters included in the physical layer trailer.

At step S1112, the reception process section 112 determines whether ornot the wireless signal is addressed to the own device on the basis ofthe recipient address identification information (RXAID) among theacquired parameters. In a case where the wireless signal is addressed tothe own device (step S1112/Yes), the reception process section 112divides the received data on the basis of a block length of apredetermined encoding process and performs the decoding process inunits of divided blocks at step S1116.

In a case where an error is detected and the error correction issuccessful as a result of the decoding process at step S1120 (stepS1120/Yes), the MPDU processor 113 acquires MPDU for which the errorcorrection has been successful and stores the MPDU in the receptionbuffer 114 at step S1124.

At step S1128, the MPDU processor 113 determines whether or not thereceived A-MPDU includes MPDU for retransmission on the basis of thesequence number information (Seq. No.) of the MPDUs acquired from thephysical layer header or the physical layer trailer. In a case where thereceived A-MPDU includes MPDU for retransmission (step S1128/Yes), theMPDU processor 113 acquires an error-free portion of MPDU received inthe past at step S1132.

At step S1136, the MPDU processor 113 determines whether or not it ispossible to restore error-free MPDU by combining respective error-freeportions from the MPDU received in the past and the MPDU forretransmission. In a case where the MPDU processor 113 determines thatit is possible to restore error-free MPDU by combining the error-freeportions (step S1136/Yes), the MPDU processor 113 restores theerror-free MPDU by performing the combining process at step S1140. Atstep S1144, the MPDU processor 113 records the sequence numberinformation (Seq. No.) of the successfully restored MPDU as informationfor ACK.

In a case where the MPDU processor 113 determines that it is notpossible to restore error-free MPDU by combining the error-free portionsat step S1136 (step S1136/No), the MPDU processor 113 acquires the datalength information (Length) of the MPDUs at step S1148, and specifiesand stores a range in a block having the error at step S1152.Furthermore, in a case where the received A-MPDU includes no MPDU forretransmission at step S1128 (step S1128/No), the process moves to stepS1156.

At step S1156, the MPDU processor 113 determines whether or not theprocess is complete to the MPDU at the end included in the A-MPDU. In acase where it is determined that the process is not complete to the MPDUat the end (step S1156/No), the process moves to step S1116 and theabove-described process on each MPDU is repeated.

In a case where it is determined that the process is complete to theMPDU at the end (step S1156/Yes), the transmission process section 115reads out the information for ACK at step S1160 and constructs, forexample, a block ACK frame including the sequence number information(Seq. No.) of the MPDUs received with no error at step S1164. At stepS1168, the antenna controller 111 transmits the constructed block ACKframe, and the process ends.

It should be noted that, in a case where the detected wireless signal isnot compatible with the present disclosure at step S1104 (stepS1104/No), and in a case where the data is normally received (stepS1172/Yes), the MPDU processor 113 acquires the normally received MPDUsand stores the acquired MPDUs in the reception buffer 114 at step S1176.At step S1180, the MPDU processor 113 records the sequence numberinformation (Seq. No.) of the normally received MPDU as information forACK. In a case where the data is not normally received at step S1172(step S1172/No), the process moves to step S1184.

At step S1184, the MPDU processor 113 determines whether or not theprocess is complete to the MPDU at the end included in the A-MPDU. In acase where it is determined that the process is not complete to the MPDUat the end (step S1184/No), the process moves to step S1172 and theabove-described process on each MPDU is repeated.

In a case where it is determined that the process is complete to theMPDU at the end (step S1184/Yes), the process moves to step S1160. Thatis, the processes at step S1160 and the following steps are performed,thereby transmitting a block ACK frame. The process ends. It should benoted that the above-described flowchart is merely an example, and ismodifiable as appropriate.

3. MODIFICATION EXAMPLES

The operations of the AP 200 and the STA 100 have been described above.Next, modification examples of the present disclosure are described.

3-1. Application to MPDU Shorter than Block Length

In the above-described embodiment, the block length of the encodingprocess is shorter than that of the MPDU that is a data unit in whichthe retransmission process is performed. However, the block length ofthe encoding process may be greater than that of the MPDU. The followingtherefore describes a case where the block length of the encodingprocess is greater than that of the MPDU with reference to FIGS. 15 and16.

In an example illustrated in FIG. 15, the transmitter aggregates firstMPDU (1st MPDU) to seventh MPDU (7th MPDU). The transmitter then appendsPadding (Pad) to MPDU shorter than the block length as necessary. Forexample, the data length of the 1st MPDU is shorter than the blocklength, and therefore the transmitter appends Padding (Pad) thereto.Furthermore, a total value of the respective data lengths of the 3rdMPDU and the 4th MPDU is also shorter than the block length, andtherefore the transmitter appends Padding (Pad) thereto. By contrast,the data length of the 2nd MPDU is equal to the block length, andtherefore the transmitter does not append Padding (Pad) thereto.

In addition, in a case where a total value of the respective datalengths of a plurality of MPDUs is equal to the block length, thetransmitter stores the plurality of MPDUs in one block without appendingPadding (Pad) thereto. For example, a total value of the respective datalengths of the 5th MPDU, the 6th MPDU, and the 7th MPDU is equal to theblock length, and therefore the transmitter stores these MPDUs in oneblock.

The contents of the encoding process illustrated in FIG. 15 are similarto those have been described with reference to FIG. 5. Accordingly,detailed description thereof is omitted. That is, the transmitterperforms the encoding process by using, for example, an RS (255, 239)code.

The transmitter then generates a data frame obtained by appending thepredetermined preamble (Preamble), the physical layer header (Header),and the physical layer trailer (Trailer) to the data subjected to theencoding process. The configuration of the physical layer header(Header) and the physical layer trailer (Trailer) is similar to theconfiguration described with reference to FIGS. 2 and 3. Accordingly,description thereof is omitted.

In addition, the contents of the decoding process illustrated in FIG. 16are similar to those have been described with reference to FIG. 6.Accordingly, detailed description thereof is omitted. That is, thereceiver acquires various parameters included in the physical layerheader (Header) or the physical layer trailer (Trailer), and grasps theblock length of the encoding process on the basis of the encoding formatinformation (Type) or the like of the parameters. The receiver thenperforms error detection and error correction by extracting redundancyinformation from the encoded information.

Here, the receiver stores a block for which the error correction hasbeen unsuccessful. Similarly to the embodiment described above, thereceiver then requests the transmitter to retransmit the MPDU for whichthe error correction has been unsuccessful, and restores error-free MPDUby combining respective error-free blocks from the retransmitted MPDUand the MPDU transmitted in the past, thereby succeeding in thereception process.

As described above, the present disclosure is applicable to the casewhere the block length of the encoding process is greater than that ofthe MPDU.

3-2. Application to A-MSDU

As for the above-described embodiment, a case where the presentdisclosure is applied to A-MPDU has been described. However, the presentdisclosure may be applied to A-MSDU. The following therefore describes acase where the present disclosure is applied to A-MSDU with reference toFIGS. 17 to 19.

First, a physical layer header (Header) and a physical layer trailer(Trailer) of the A-MSDU are described with reference to FIG. 17. Asillustrated in FIG. 17, the physical layer header (Header) and thephysical layer trailer (Trailer) of the A-MSDU include information suchas recipient address identification information (RXAID), transmitteraddress identification information (TXAID), encoding format information(Type), encoding process block length information (Block Size), datalength information (Total Length) of the entire A-MSDU, information(MSDU Count) of the number of MSDUs to be aggregated, sequence numberinformation (Seq. No.) of the MSDUs and data length information (Length)of the MSDU as the information for use in identification of each MSDU,and an error detection code (CRC).

It should be noted that FIG. 17 is merely an example, but theconfiguration of the physical layer header (Header) and the physicallayer trailer (Trailer) of the A-MSDU is not limited thereto. Forexample, the sequence number information (Seq. No.) of the MSDUs may bereplaced with a starting sequence number (Start Sequence) andinformation (Sequence Bitmap) indicating the sequence number of theMSDUs included in the subsequent A-MSDU in a bitmap format.

Next, an overview of an encoding process is described with reference toFIG. 18.

In an example illustrated in FIG. 18, the transmitter targets, for theencoding process, data obtained by aggregating first MSDU (1st MSDU) tosixth MSDU (6th MSDU) and appending Padding (Pad) thereto asappropriate.

The contents of the encoding process illustrated in FIG. 18 are similarto those have been described with reference to FIG. 5. Accordingly,detailed description thereof is omitted. That is, the transmitterperforms the encoding process by using, for example, an RS (255, 239)code.

The transmitter then generates a data frame obtained by appending thepredetermined preamble (Preamble), the physical layer header (Header),and the physical layer trailer (Trailer) to the data subjected to theencoding process.

In addition, the contents of the decoding process illustrated in FIG. 19are similar to those have been described with reference to FIG. 6.Accordingly, detailed description thereof is omitted. That is, thereceiver acquires various parameters included in the physical layerheader (Header) or the physical layer trailer (Trailer), and grasps theblock length of the encoding process on the basis of the encoding formatinformation (Type) or the like of the parameters. The receiver thenperforms error detection and error correction by extracting redundancyinformation from the encoded information.

Here, the receiver stores a block for which an error has been detectedand the error correction has been unsuccessful. More specifically, thereceiver specifies MSDU for which the error correction has beenunsuccessful and a range in the MSDU for which the error correction hasbeen unsuccessful on the basis of the data length information (Length)of each MSDU and the sequence number information (Seq. No.) of each MSDUincluded in the physical layer header (Header) or the physical layertrailer (Trailer), and stores the information.

The receiver then requests the transmitter to retransmit the MPDU forwhich the error correction has been unsuccessful, by transmitting ablock ACK frame and the like to the transmitter, and restores error-freeMSDU by combining respective error-free blocks from the retransmittedMSDU and the MSDU transmitted in the past, thereby succeeding in thereception process.

As described above, the present disclosure is also applicable to A-MSDU.

3-3. Case where MPDU Is Configured by Aggregating Plurality of MSDUs

Next, a case where an MPDU is configured by aggregating a plurality ofMSDUs is described.

For example, as illustrated in FIG. 20, the transmitter may construct aframe by aggregating six MSDUs (1st MSDU to 6th MSDU) into one MPDU (1stMPDU). The transmitter then appends delimiter information (Delimiter)and an error detection code (CRC) to the MPDU. It should be noted thatthe contents of the delimiter information (Delimiter) are similar to thecontents described with reference to FIG. 4. Accordingly, descriptionthereof is omitted.

In addition, a plurality of MPDUs may be configured instead of one MPDUby aggregating a plurality of MSDUs. For example, as illustrated in FIG.21, the transmitter may aggregate three MSDUs (1st MSDU to 3rd MSDU)into one MPDU (1st MPDU), aggregate other three MSDUs (4th MSDU to 6thMSDU) into another MPDU (2nd MPDU), and then further aggregate the twoMPDUs to construct one frame.

In this case, similarly to the above, the receiver restores error-freeMSDU by combining respective error-free blocks of retransmitted MSDU andMSDU transmitted in the past, thereby succeeding in the receptionprocess.

As described above, the present disclosure is also applicable to thecase where MPDU is configured by aggregating a plurality of MSDUs.

3-4. Variations of Storage Position of Physical Layer Header

Next, variations of the storage position of the physical layer header(Header) are described with reference to FIGS. 22 to 29.

In the above-described example, the physical layer header (Header) isstored between the predetermined preamble (Preamble) and the MPDU at thebeginning of the A-MPDU as illustrated in FIG. 22 (it should be notedthat the physical layer trailer (Trailer) including the same informationas that of the physical layer header (Header) is also appended to theend). However, the storage position of the physical layer header(Header) is not limited thereto.

For example, as illustrated in FIG. 23, the physical layer header(Header) may be stored between the PLCP header and the MPDU at thebeginning of the A-MPDU. Here, in FIG. 23, a legacy short training field(L-STF), a legacy long training field (L-LTF), legacy signaling (L-SIG),high efficiency signaling A (HE-SIG-A), a high efficiency short trainingfield (HE-STF), a predetermined number of high efficiency short trainingfields (HE-LTF), and high efficiency signaling B (HE-SIG-B) are includedas a traditional preamble.

In addition, as illustrated in FIG. 24, the physical layer header(Header) may be stored between a predetermined number of high efficiencyshort training fields (HE-LTF) and the high efficiency signaling B(HE-SIG-B).

In addition, as illustrated in FIG. 25, the physical layer header(Header) may be stored between the high efficiency signaling A(HE-SIG-A) and the high efficiency short training field (HE-STF).

In addition, as illustrated in FIG. 26, the physical layer header(Header) may be stored between the legacy signaling (L-SIG) and the highefficiency signaling A (HE-SIG-A).

In addition, as illustrated in FIG. 27, the physical layer header(Header) may be configured as a portion of the high efficiency signalingA (HE-SIG-A).

In addition, as illustrated in FIG. 28, the physical layer header(Header) may be configured as a portion of the high efficiency signalingB (HE-SIG-B).

In addition, as illustrated in FIG. 29, the physical layer header(Header) may be configured as a portion of newly defined high efficiencysignaling C (HE-SIG-C).

It should be noted that, in FIGS. 23 to 29, the physical layer trailer(Trailer) including the same information as that of the physical layerheader (Header) may be appended to the end of the frame as in FIG. 22,or only the physical layer trailer (Trailer) may be appended to the endof the frame with the physical layer header (Header) omitted.

As described above, the storage position of the physical layer header(Header) may take various variations.

4. APPLICATION EXAMPLES

The technology according to the present disclosure is applicable tovarious products. For example, the STA 100 may be achieved as a mobileterminal such as a smartphone, tablet PC (Personal Computer), notebookPC, a portable game terminal, or a digital camera; a fixed terminal suchas a television receiver, a printer, a digital scanner, or a networkstorage; or an on-vehicle terminal such as a car navigation apparatus.In addition, the STA 100 may be achieved as a terminal (also referred toas MTC (Machine Type Communication) terminal) that performs M2M (MachineTo Machine) communication such as a smart meter, a vending machine, aremote monitoring device, or a POS (Point Of Sale) terminal. Further,the STA 100 may be a wireless communication module (for example,integrated circuit module including one die) mounted on these terminals.

By contrast, for example, the AP 200 may be achieved as a wireless LANaccess point (also referred to as wireless base station) with or withouta router function. In addition, the AP 200 may be achieved as a mobilewireless LAN router. Further, the AP 200 may be a wireless communicationmodule (for example, integrated circuit module including one die)mounted on these devices.

4-1. First Application Example

FIG. 30 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which the technology according tothe present disclosure may be applied. The smartphone 900 includes aprocessor 901, a memory 902, a storage 903, an external couplinginterface 904, a camera 906, a sensor 907, a microphone 908, an inputdevice 909, a display device 910, a speaker 911, a wirelesscommunication interface 913, an antenna switch 914, an antenna 915, abus 917, a battery 918, and an auxiliary controller 919.

The processor 901 may be, for example, CPU (Central Processing Unit) orSoC (System on Chip), and controls the functions of an application layerand other layers of the smartphone 900. The memory 902 includes RAM(Random Access Memory) and ROM (Read Only Memory), and stores a programto be executed by the processor 901 and data. The storage 903 mayinclude a storage medium such as a semiconductor memory or a hard disk.The external coupling interface 904 is an interface for coupling anexternally attached device such as a memory card or a USB (UniversalSerial Bus) device to the smartphone 900.

The camera 906 includes, for example, an imaging element such as CCD(Charge Coupled Device) or CMOS (Complementary Metal OxideSemiconductor), and generates a captured image. The sensor 907 mayinclude a sensor group including, for example, a positioning sensor, agyro sensor, a geomagnetic sensor, an acceleration sensor and the like.The microphone 908 converts a sound that is inputted into the smartphone900 to a sound signal. The input device 909 includes, for example, atouch sensor that detects a touch onto a screen of the display device910, a key pad, a keyboard, a button, a switch, or the like, andreceives an operation or an information input from a user. The displaydevice 910 includes a screen such as a liquid crystal display (LCD) oran organic light-emitting diode (OLED) display, and displays an outputimage of the smartphone 900. The speaker 911 converts the sound signalthat is outputted from the smartphone 900 to a sound.

The wireless communication interface 913 supports one or more ofwireless LAN standards such as IEEE 802.11a, 11b, 11g, 11n, 11ac, and11ad, and executes wireless communication. The wireless communicationinterface 913 may communicate with another device via a wireless LANaccess point in an infrastructure mode. Furthermore, the wirelesscommunication interface 913 may directly communicate with another devicein an ad-hoc mode or a direct communication mode such as Wi-Fi Direct(registered trademark). It should be noted that, in Wi-Fi Direct, unlikethe ad-hoc mode, one of two terminals operates as an access point, butthese terminals directly communicate with each other. Typically, thewireless communication interface 913 may include a baseband processor,an RF (Radio Frequency) circuit, a power amplifier, and the like. Thewireless communication interface 913 may be a one-chip module in which amemory that stores a communication control program, a processor thatexecutes the program, and a related circuit are integrated. The wirelesscommunication interface 913 may support another type of wirelesscommunication scheme such as a short-range wireless communicationscheme, a near field communication scheme, or a cellular communicationscheme in addition to a wireless LAN scheme. The antenna switch 914switches a coupling destination of the antenna 915 between a pluralityof circuits (for example, circuits for different wireless communicationschemes) included in the wireless communication interface 913. Theantenna 915 includes one or more antenna elements (for example, aplurality of antenna elements included in a MIMO antenna), and is usedfor transmission and reception of the wireless signal by the wirelesscommunication interface 913.

It should be noted that the smartphone 900 is not limited to the exampleillustrated in FIG. 30, but may include a plurality of antennas (forexample, an antenna for wireless LAN and an antenna for a near fieldcommunication scheme). In that case, the antenna switch 914 may beomitted from the configuration of the smartphone 900.

The bus 917 couples the processor 901, the memory 902, the storage 903,the external coupling interface 904, the camera 906, the sensor 907, themicrophone 908, the input device 909, the display device 910, thespeaker 911, the wireless communication interface 913, and the auxiliarycontroller 919 to each other. The battery 918 supplies electric power toeach block of the smartphone 900 illustrated in FIG. 30 via a powersupply line that is partially illustrated in the diagram as a dashedline. The auxiliary controller 919, for example, operates a minimallynecessary function of the smartphone 900 in a sleep mode.

It should be noted that the smartphone 900 may operate as a wirelessaccess point (software AP) through the processor 901 executing anapplication-level access point function. In addition, the wirelesscommunication interface 913 may have a wireless access point function.

4-2. Second Application Example

FIG. 31 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus 920 to which the technologyaccording to the present disclosure may be applied. The car navigationapparatus 920 includes a processor 921, a memory 922, a GPS (GlobalPositioning System) module 924, a sensor 925, a data interface 926, acontent player 927, a storage medium interface 928, an input device 929,a display device 930, a speaker 931, a wireless communication interface933, an antenna switch 934, an antenna 935, and a battery 938.

The processor 921 may be, for example, CPU or SoC, and controls thenavigation function and the other functions of the car navigationapparatus 920. The memory 922 includes RAM and ROM, and stores a programto be executed by the processor 921 and data.

The GPS module 924 uses a GPS signal received from a GPS satellite tomeasure the position (e.g., latitude, longitude, and altitude) of thecar navigation apparatus 920. The sensor 925 may include a sensor groupincluding, for example, a gyro sensor, a geomagnetic sensor, anatmospheric pressure sensor and the like. The data interface 926 is, forexample, coupled to an in-vehicle network 941 via a terminal that is notillustrated, and acquires data such as vehicle speed data generated onthe vehicle side.

The content player 927 reproduces content stored in a storage medium(e.g., CD or DVD) to be inserted into the storage medium interface 928.The input device 929 includes, for example, a touch sensor that detectsa touch onto a screen of the display device 930, a button, a switch, orthe like, and receives an operation or an information input from a user.The display device 930 includes a screen such as LCD or an OLED display,and displays an image of the navigation function or the reproducedcontent. The speaker 931 outputs a sound of the navigation function orthe reproduced content.

The wireless communication interface 933 supports one or more ofwireless LAN standards such as IEEE 802.11a, 11b, 11g, 11n, 11ac, and11ad, and executes wireless communication. The wireless communicationinterface 933 may communicate with another device via a wireless LANaccess point in an infrastructure mode. Furthermore, the wirelesscommunication interface 933 may directly communicate with another devicein an ad-hoc mode or a direct communication mode such as Wi-Fi Direct.Typically, the wireless communication interface 933 may include abaseband processor, an RF circuit, a power amplifier, and the like. Thewireless communication interface 933 may be a one-chip module in which amemory that stores a communication control program, a processor thatexecutes the program, and a related circuit are integrated. The wirelesscommunication interface 933 may support another type of wirelesscommunication scheme such as a short-range wireless communicationscheme, a near field communication scheme, or a cellular communicationscheme in addition to a wireless LAN scheme. The antenna switch 934switches a coupling destination of the antenna 935 between a pluralityof circuits included in the wireless communication interface 933. Theantenna 935 includes one or more antenna elements, and is used fortransmission and reception of the wireless signal by the wirelesscommunication interface 933.

It should be noted that the car navigation apparatus 920 is not limitedto the example illustrated in FIG. 31, but may include a plurality ofantennas. In that case, the antenna switch 934 may be omitted from theconfiguration of the car navigation apparatus 920.

The battery 938 supplies electric power to each block of the carnavigation apparatus 920 illustrated in FIG. 31 via a power supply linethat is partially illustrated in the diagram as a dashed line. Inaddition, the battery 938 accumulates the electric power supplied fromthe vehicle side.

In addition, the technology according to the present disclosure may alsobe achieved as an in-vehicle system (or a vehicle) 940 including one ormore blocks of the car navigation apparatus 920 described above, thein-vehicle network 941, and a vehicle module 942. The vehicle module 942generates vehicle data such as vehicle speed, engine speed, and troubleinformation, and outputs the generated data to the in-vehicle network941.

4-3. Third Application Example

FIG. 32 is a block diagram illustrating an example of a schematicconfiguration of a wireless access point 950 to which the technologyaccording to the present disclosure may be applied. The wireless accesspoint 950 includes a controller 951, a memory 952, an input device 954,a display device 955, a network interface 957, a wireless communicationinterface 963, an antenna switch 964, and an antenna 965.

The controller 951 may be, for example, CPU or DSP (Digital SignalProcessor), and causes various functions (for example, accessrestriction, routing, encryption, firewall, log management, and thelike) in an IP (Internet Protocol) layer and higher layers of thewireless access point 950 to operate. The memory 952 includes RAM andROM, and stores a program to be executed by the controller 951 andvarious kinds of control data (for example, terminal lists, routingtables, encryption keys, security settings, logs, and the like).

The input device 954 includes, for example, a button, a switch, or thelike, and receives an operation from a user. The display device 955includes an LED lamp and the like, and displays an operation status ofthe wireless access point 950.

The network interface 957 is a wired communication interface forcoupling the wireless access point 950 to a wired communication network958. The network interface 957 may include a plurality of couplingterminals. The wired communication network 958 may be LAN such asEthernet (registered trademark) or may be WAN (Wide Area Network).

The wireless communication interface 963 supports one or more ofwireless LAN standards such as IEEE 802.11a, 11b, 11g, 11n, 11ac, and11ad, and provides wireless coupling as an access point for a terminalin the vicinity. Typically, the wireless communication interface 963 mayinclude a baseband processor, an RF circuit, a power amplifier, and thelike. The wireless communication interface 963 may be a one-chip modulein which a memory that stores a communication control program, aprocessor that executes the program, and a related circuit areintegrated. The antenna switch 964 switches a coupling destination ofthe antenna 965 between a plurality of circuits included in the wirelesscommunication interface 963. The antenna 965 includes one or moreantenna elements, and is used for transmission and reception of thewireless signal by the wireless communication interface 963.

5. CONCLUSION

As described above, the wireless LAN system according to the presentdisclosure performs a combining process of respective error-free blocksfrom MPDU for which the reception process has been unsuccessful andretransmitted MPDU to restore the MPDU, thereby succeeding in thereception process.

This enables the wireless LAN system to achieve more appropriateretransmission control. More specifically, even if a block in MPDUincludes an error, the receiver is able to use error-free portions ofthe MPDU for the combining process instead of discarding the whole MPDU.It is therefore possible to restore error-free MPDU with a higherprobability. Furthermore, the receiver is able to perform the combiningprocess without depending on the block length of the encoding process bymanaging an error-containing portion of the MPDU in units of bytes.

Furthermore, the wireless LAN system includes, in a physical layerheader, information for use in identification of aggregated MPDUs inA-MPDU and appends a physical layer trailer including the sameinformation to the end of a data frame. This enables the wireless LANsystem to identify each MPDU even if the data length informationincluded in the delimiter information is incorrect.

Furthermore, the wireless LAN system is able to store a plurality ofidentical retransmission MPDUs in A-MPDU as long as a frameconfiguration of the A-MPDU has the capacity. This makes it possible toincrease the possibility of succeeding in the combining process.

A preferred embodiment(s) of the present disclosure has/have beendescribed above in detail with reference to the accompanying drawings,but the technical scope of the present disclosure is not limited to suchan embodiment(s). A person skilled in the art may find variousalterations and modifications within the scope of the appended claims,and it should be understood that they naturally come under the technicalscope of the present disclosure.

Further, the effects described herein are merely illustrative andexemplary, and not limitative. That is, the technology according to thepresent disclosure may exert other effects that are apparent to thoseskilled in the art from the description herein, in addition to theabove-described effects or in place of the above-described effects.

It should be noted that the following configurations also fall withinthe technical scope of the present disclosure.

-   ( 1)

A wireless LAN communication device including:

a generator that generates a data frame for which a data unit in whichan encoding process is performed and a data unit in which aretransmission process is performed are different from each other, theencoding process making it possible to determine whether or not decodingis successful; and

a transmission section that transmits the data frame.

-   (2)

The wireless LAN communication device according to (1), in which thedata unit in which the encoding process is performed is smaller than thedata unit in which the retransmission process is performed.

-   (3)

The wireless LAN communication device according to (1), in which thedata unit in which the encoding process is performed is larger than thedata unit in which the retransmission process is performed.

-   (4)

The wireless LAN communication device according to any one of (1) to(3), in which the generator generates the data frame through aggregationof data in the data unit in which the retransmission process isperformed.

-   (5)

The wireless LAN communication device according to (4), in which thegenerator performs the aggregation until a predetermined data length isreached.

-   (6)

The wireless LAN communication device according to (5), in which thedata frame includes A-MPDU obtained by aggregating MPDUs or A-MSDUobtained by aggregating MSDUs.

-   (7)

The wireless LAN communication device according to (5) or (6), in whichthe generator includes a plurality of identical pieces of data forretransmission in the data frame.

-   (8)

The wireless LAN communication device according to any one of (1) to(7), in which the generator appends, to the data frame, information foruse in identification of data to be subjected to the retransmissionprocess.

-   (9)

The wireless LAN communication device according to (8), in which theinformation for use in identification of the data includes data lengthinformation and sequence number information of the data to be subjectedto the retransmission process.

-   (10)

The wireless LAN communication device according to (8) or (9), in whichthe generator includes the information for use in identification of thedata in a physical layer header or a physical layer trailer appended tothe data frame.

( 11)

A wireless LAN communication method that is executed by a computer, thewireless LAN communication method including:

generating a data frame for which a data unit in which an encodingprocess is performed and a data unit in which a retransmission processis performed are different from each other, the encoding process makingit possible to determine whether or not decoding is successful; and

transmitting the data frame.

-   (12)

A wireless LAN communication device including:

a reception section that receives a data frame for which a data unit inwhich an encoding process is performed and a data unit in which aretransmission process is performed are different from each other, theencoding process making it possible to determine whether or not decodingis successful; and

a reception process section that performs a reception process includingdecoding the data frame.

-   (13)

The wireless LAN communication device according to (12), in which thereception process section specifies a range in data for which thereception process has been unsuccessful, and performs a combiningprocess with a portion of retransmitted data.

-   (14)

The wireless LAN communication device according to (12) or (13), inwhich the data frame is generated through aggregation of data in thedata unit in which the retransmission process is performed.

-   (15)

The wireless LAN communication device according to (14), in which thedata frame includes A-MPDU obtained by aggregating MPDUs or A-MSDUobtained by aggregating MSDUs.

-   (16)

The wireless LAN communication device according to (14) or (15), inwhich the reception process section performs the reception process byusing a plurality of identical pieces of data for retransmissionincluded in the data frame.

-   (17)

The wireless LAN communication device according to any one of (12) to(16), in which the reception process section performs the receptionprocess on a basis of information for use in identification of data tobe subjected to the retransmission process, the information beingappended to the data frame.

-   (18)

The wireless LAN communication device according to (17), in which theinformation for use in identification of the data includes data lengthinformation and sequence number information of the data to be subjectedto the retransmission process.

-   (19)

The wireless LAN communication device according to (17) or (18), inwhich the information for use in identification of the data is includedin a physical layer header or a physical layer trailer appended to thedata frame.

-   (20)

A wireless LAN communication method that is executed by a computer, thewireless LAN communication method including:

receiving a data frame for which a data unit in which an encodingprocess is performed and a data unit in which a retransmission processis performed are different from each other, the encoding process makingit possible to determine whether or not decoding is successful; and

performing a reception process including decoding the data frame.

REFERENCE SIGNS LIST

-   100 STA-   200 AP-   110, 210 Wireless communication unit-   111, 211 Antenna controller-   112, 212 Reception process section-   113, 213 MPDU processor-   114, 214 Reception buffer-   115, 215 Transmission process section-   116, 216 MPDU processor-   117, 217 Transmission buffer-   120, 220 Wireless interface-   130, 230 Controller-   140, 240 Wired interface-   150, 250 Input unit-   160, 260 Output unit

1. A wireless LAN communication device comprising circuitry configuredto: generate a data frame comprising a first data unit in which anencoding process is performed on first data and a second data unit inwhich a retransmission process of the first data is performed, whereinthe first data unit and the second data unit are different from eachother, the encoding process making it possible to determine whether ornot the first data of the first data unit is successfully decoded;append, to the data frame, information for use in identification of datato be subjected to the retransmission process; and transmit the dataframe, wherein the information for use in identification of the data tobe subjected to the retransmission process includes data lengthinformation and sequence number information of the data.
 2. The wirelessLAN communication device according to claim 1, wherein the first dataunit in which the encoding process is performed is smaller than thesecond data unit in which the retransmission process is performed. 3.The wireless LAN communication device according to claim 1, wherein thefirst data unit in which the encoding process is performed is largerthan the second data unit in which the retransmission process isperformed.
 4. The wireless LAN communication device according to claim1, wherein the circuitry is further configured to generate the dataframe through aggregation of data of data units in which theretransmission process is performed.
 5. The wireless LAN communicationdevice according to claim 4, wherein the circuitry is further configuredto perform the aggregation until a predetermined data length is reached.6. The wireless LAN communication device according to claim 5, whereinthe data frame comprises A-MPDU obtained by aggregating MPDUs or A-MSDUobtained by aggregating MSDUs.
 7. The wireless LAN communication deviceaccording to claim 5, wherein the circuitry is further configured togenerate the data frame with a plurality of identical pieces of data forretransmission.
 8. The wireless LAN communication device according toclaim 1, wherein the circuitry is further configured to include theinformation for use in identification of the data in a physical layerheader or a physical layer trailer appended to the data frame.
 9. Awireless LAN communication method that is executed by a computer, thewireless LAN communication method comprising: generating a data framecomprising a first data unit in which an encoding process is performedon first data and a second data unit in which a retransmission processof the first data is performed, wherein the first data unit and thesecond data unit are different from each other, the encoding processmaking it possible to determine whether or not the first data of thefirst data unit is successfully decoded; appending, to the data frame,information for use in identification of data to be subjected to theretransmission process; and transmitting the data frame, wherein theinformation for use in identification of the data to be subjected to theretransmission process includes data length information and sequencenumber information of the data.
 10. The wireless LAN communicationmethod according to claim 9, wherein the first data unit in which theencoding process is performed is smaller than the second data unit inwhich the retransmission process is performed.
 11. The wireless LANcommunication method according to claim 9, wherein the first data unitin which the encoding process is performed is larger than the seconddata unit in which the retransmission process is performed.
 12. Awireless LAN communication device comprising circuitry configured to:receive a data frame comprising a first data unit in which an encodingprocess is performed on first data and a second data unit in which aretransmission process of the first data is performed, wherein the firstdata unit and the second data unit are different from each other, theencoding process making it possible to determine whether or not thefirst data of the first data unit is successfully decoded; and decodethe data frame, wherein the received data frame includes information foruse in identification of data to subjected to the retransmissionprocess, and wherein the information for use in identification of thedata to subjected to the retransmission process includes data lengthinformation and sequence number information of the data.
 13. Thewireless LAN communication device according to claim 12, wherein thecircuitry is further configured to: specify a range in data for whichthe reception process has been unsuccessful; and perform a combiningprocess with a portion of retransmitted data.
 14. The wireless LANcommunication device according to claim 13, wherein the circuitry isfurther configured to perform the combining process by combining aportion of the first data of the first data unit that was decodedsuccessfully with a portion of the first data from the second data unit,the portion of the first data from the second data unit corresponding tothe portion of the first data of the first data unit that was notdecoded successfully.
 15. The wireless LAN communication deviceaccording to claim 12, wherein the data frame is generated throughaggregation of data of data units in which the retransmission process isperformed.
 16. The wireless LAN communication device according to claim15, wherein the data frame comprises A-MPDU obtained by aggregatingMPDUs or A-MSDU obtained by aggregating MSDUs.
 17. The wireless LANcommunication device according to claim 14, wherein the received dataframe includes a plurality of identical pieces of data forretransmission.
 18. The wireless LAN communication device according toclaim 12, wherein the information for use in identification of the datais included in a physical layer header or a physical layer trailerappended to the data frame.
 19. A wireless LAN communication method thatis executed by a computer, the wireless LAN communication methodcomprising: receiving a data frame comprising a first data unit in whichan encoding process is performed on first data and a second data unit inwhich a retransmission process of the first data is performed, whereinthe first data unit and the second data unit are different from eachother, the encoding process making it possible to determine whether ornot the first data of the first data unit is successfully decoded; anddecoding the data frame, wherein the received data frame includesinformation for use in identification of data to subjected to theretransmission process, and wherein the information for use inidentification of the data to subjected to the retransmission processincludes data length information and sequence number information of thedata.
 20. The wireless LAN communication method according to claim 19,further comprising: specifying a range in data for which the receptionprocess has been unsuccessful; and performing a combining process with aportion of retransmitted data.